The right use of religious sculptures was an important point of discussion in the Middle Ages. The ban on carved images (Exodus 20:3) stood in the background of this discussion. Reformers like Zwingli and Bucer took a clearly anaphoric view in this discussion, but for Luther it was part of the so-called ‘adiaphora’, things that were unimportant from the point of view of salvation.
According to Luther, by presenting people the right images, people can understand more clearly and thus support the Gospel. They remind observers of the work of God, draw attention to piety, and keep the devil away from the faithful that way. So, sculptures have a didactic and catechetical function for Luther by the interposition of faith.
According to Luther, abuse arises when people place their faith in sculptures, worshipping and admiring them. By so doing, they make sculptures into deities and they attempt to earn merit with God through such works. To counteract this, it is necessary that the hearts of the believers are taught the truth by sermons and pastoral conversations. If sculptures are set up and become a source of false trust, then they have to be removed from the sanctuary, when the council says so. Luther denounces iconoclasm (as organized by Andreas Karlstadt in Wittenberg) as legalism. So, Luther does not have a problem with images, as long as they are rightly apprehended.